RT Journal Article SR Electronic T1 Principles of Clinical Measurement JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 941 OP 941 DO 10.1136/jcp.34.8.941-d VO 34 IS 8 A1 Green, HL YR 1981 UL http://jcp.bmj.com/content/34/8/941.4.abstract AB